Currently, UN and NATO missions involve very small contingents, comprised mostly of officers and senior NCMs as they tend to be in advisory/staff positions. Any junior NCMs (i.e. corporals and below) tend to be in support trades (RMS, supply, etc) in direct support of the Canadian contingent (whose support requirements are generally quite small). Unless there is a requirement for general duty personnel, the chances of an OS boatswain being selected are pretty much next to nil (never say never, but...).
To be honest, your most realistic option to get out and see the world is to get yourself on a ship deployment. If you're not interested in doing this, then you really need to assess your membership in the Naval Reserve and consider a transfer. Your future as a boatswain who doesn't want to go to sea is less than limited.
Having said that, just how much sea experience do you have upon which to make this judgement? If you haven't actually tried it, perhaps you need to. I think you owe it to yourself, as well as all the other applicants whom you beat out for your position when you enrolled. OT applicants who have given things an honest try and are thus making an informed decision also tend to fare better in the process.